The present invention relates to a mounting element for mounting an object to a support structure. More particularly, it relates to a mounting element which includes an expansion sleeve member insertable into a mounting hole of a support structure, and an expander member screwable into the expansion sleeve so as to expand and to fix the same in the support structure and also to support objects to be mounted.
Mounting elements of the above-mentioned general type are known in the art. In a known mounting element, the expansion sleeve member is composed of synthetic plastic material and has a longitudinal opening for screwing in of the expander member, and advantageously a longitudinal slot. The expander member has a round thread with a narrowing thread outlet extending toward a pointed end of the expander member. Anchoring of the expansion sleeve member of synthetic plastic material in the mounting hole of the support structure is generally attained by screwing in of the expander member formed as a wooden screw. The latter is provided with a thread having a pointed profile. When the screw is screwed into the expansion sleeve, the peaks of the thread are driven very deep into the material of the expansion sleeve member and thereby weaken the cross-section of the expansion sleeve member. Furthermore, the flanks of the thread displace only part of the material of the expansion sleeve member towards the outer wall, whereas the major part of the material of the expansion sleeve member is displaced in a longitudinal direction so that the expansion sleeve member is stretched. Thereby, the shape of the thread of the expander member or mounting screw in connection with the expansion sleeve member of synthetic plastic material is not suitable for optimum anchoring value.
In order to eliminate the above-mentioned disadvantages, it has been proposed in the German Gebrauchsmuster 7,825,757 to use a mounting element in which the expander member or mounting screw has a round thread. The round thread provides not only improvement of the flanks of the expander member because of the favorable fiber location in the expander member, but also results in a considerably greater radial driving of the material of the expansion sleeve member into a wall of the mounting hole in a support structure. This leads to a considerably stronger wedging and thereby anchoring of the expansion sleeve member in the mounting hole. The thread domes are pressed into the material of the expansion sleeve member over a great surface and thereby the outer face of the expansion sleeve member is curved in correspondence with the pitch of the round thread. This causes a wave-like distribution of an expansion pressure with increased clamping force in the region of the thread domes. Since the round thread engages in the material of the expansion sleeve member only to a small depth, the resistance to screwing in of the expander member into the expansion sleeve member is reduced as compared with the wooden screws with threads of conventional shapes.
When the mounting element disclosed in the above-mentioned Gebrauchsmuster is utilized for anchoring in soft materials, such as gas concrete, hollow bricks and the like, a smaller expansion pressure takes place because of the smaller strength of the material. This leads to the fact that the round thread engages in the material of the expansion sleeve member with a smaller depth and the holding value between the expander member and the expansion member reduces because of reduced connection therebetween.